We shall continue working on: a) the factors controlling the methylation potential of brain tissue in the preconvulsant state; b) transfer RNA methylation, both homologous and heterologous, in an attempt to characterize the cell-specific nature of this process during brain maturation; c) the interactions of mutually competing methylating systems, such as those for histamine on one hand and for the "microamines" tyramine and tryptamine, on the other and d) the details of the involvement of 5-hydroxytryptamine in MSO seizure genesis. Emphasis will focus on those aspects which will seem of more interest and of more relevance to the central problem at issue: How does methionine sulfoximine work to induce recurrent and non-lethal seizures? BIBLIOGRAPHIC REFERENCES: Azcurra, J.M., Sellinger, O.Z. and Carrasco, A.E. "In vivo labelling of cytoplasmic RNA in neurons of the immature brain cortex." Brain Res., 86, 144-149 (1975). Schatz, R.A. and Sellinger, O.Z. "Effect of methionine and methionine sulfoximine on rat brain S-adenosyl-L-methionine levels. J. Neurochem. 24, 63-66 (1975).